


The Experiment

by LocalGrimyTeen



Category: Invader Zim
Genre: M/M, NSFW, Oneshot, Sexual Tension, ZaDr, first fic, sexual acts, short fic, zim x dib - Freeform
Language: English
Status: Completed
Published: 2019-11-07
Updated: 2019-11-07
Packaged: 2021-01-25 00:04:43
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,674
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21347002
Author URL: https://archiveofourown.org/users/LocalGrimyTeen/pseuds/LocalGrimyTeen
Summary: It had been a month since they had made the truce. Both parties agreed and kept a mutual agreement to be civil, but it’s one autumn day that uncovers a few secrets and hidden feelings.—This is a oneshot and my first fanfic ever. Of course it had to be something like this, so I hope you enjoy!
Relationships: ZaDr - Relationship
Comments: 1
Kudos: 143





	The Experiment

It had been a month since the start of their new treaty. If I promise not to leave you alone and redundant like the rest of the life on earth then you’ll stop trying to take the planet over. Deal?  
They had made the deal after an intense fight out in space. Nothing out of the ordinary For those two, though less frequent than previous years. They were in college, after all. Studies were taken more seriously than before and that means less bickering. It brought them both down, of course. Nothing much more to live for apart from the weekly tussle followed by first aid from either party. They’d softened for each other over the years, being careful not to really injure their nemesis just in case.  
It was a rather dramatic proposition after the pure “rage of the moment” fight. Both parties were out of breath, bleeding from various places, both skin and beneath. One laid partially unconscious with their hand scrambling for what looked like some sort of wrench while the other hunched over a pool of their own bloody vomit.  
“I can’t do this any more.” It was the physically stronger of the two that decided upon this. Once the deal was hastily made, they limply made their way to the medical bay. A quick space-age patch up on both later led to a month of stasis. No real fights. No injuries.  
A whole month of accustoming themselves to actually being not-enemies. Not really friends either. Mutuals, perhaps, but whatever they identified as didn’t particularly matter to either. They found themselves rather enjoying the lack of hatred towards one another and eventually ended up in each other’s company more than they’d like to admit.  
It was a month on, as previously said, and they were free for the weekend. No college work or emergency plans to call their disinterested but tall leaders on an update. Just 48 hours of freedom, so it’s only logical that they end up watching a two day long horror movie marathon in the quieter, warmer house of the two.  
Though they enjoyed each other’s less violent company, both preferred to sit on their own side of the couch, even if the human ended up with the more uncomfortable cushion,  
“I don’t want your big human butt squashing my seat. It’s perfect as it is.” Was the smaller of the two’s response to whenever “why can’t I sit there?” Was pleaded. It would make sense if that was always his designated seat, but the right side is usually always occupied by the defective, partially disguised robot that refuses to budge no matter the reason. You could say the world was ending and it would shush you because it wanted to keep watching the static on the screen for another day or two.  
That wasn’t the case today, so both parties managed to sit as far away from one another as humanly (and inhumanly) possible. Both had their legs tucked up neatly on the seat so that their feet were almost touching, just centimetres away, and leant into their hand that was propped up on the worn down arms of the magenta chair. The party on the left, as long and gangly as he could get, is drifting away into a quick nap as his disinterest in the film growing greater by the second. The other, though looking bored, actually had their eyes glued to the screen. He wasn’t allowed to feel fear, but his chest still remained tight as he anticipates the next jump-scare. His black gloved hands clench at the seat’s fabric as he unknowingly flinches at each scare.  
It’s warm inside the house as the central heating is a lot more advanced than the usual human system (and the owner seems to like the warmth) so the thin boy sat to the left has practically stripped down to his baggy shorts and logo print t-shirt. The fact that it’s an abnormally warm autumn’s day doesn’t help the fact that his ragged cowlick keeps deciding to stick to his forehead. He doesn’t sweat a lot usually, but when he does it’s very noticeable. The tackiness of his skin and the overwhelming warmth is the only thing keeping him from falling asleep at the moment. That and the almost inaudible yelps of the person next to him. Each one piked his curiosity, not towards the movie but the source of the fear.  
“Zim, what are you doing?” He cranes his neck away from his sticky hand and towards the green skinned boy who’s now raised up, hugging his knees close to his pounding chest. Obvious fear radiates from him as he stares dead ahead towards the screen. Images of maggots squirming and wriggling about a corpse flash up as a realisation flushes the curious boy with a sly grin, “are you scared of-“  
Before the end of his smug sentence a pillow is flung at full force towards his head followed by a defensive Zim appearing over him. He’s stood on the sofa for extra height with a finger pointed towards his face in rage, but it doesn’t mask the fact that he’s a good deal shorter than the person he’s trying to intimidate. It’s been like that for a good few years now,  
“Don’t you dare assume I am scared of a silly film, Dib! I’m an elite warrior! I am scared of NOTHING!” Though his expression is full of hatred and pure anger - his body bending over the laughing yet huddled up Dib who’s fixing his wonky glasses from the impact - there was still a sense of fear. Being scared over a movie, how amateurish. How embarrassing. It was made even more embarrassing because of the childish laughter coming from the man below, “Be quiet! Cease your laugher!”  
Though the request was made with the toughest and most defensive tone possible, the embarrassment managed to visably flood through Zim with his cheeks flush with a deeper green than before. He had come to terms with being defective over the years of realisation so this release of emotion wasn’t anything shocking, however he still hated feeling it. “Just let it pass” he’s learnt from self help books and whatnot, but he’d prefer letting his Pak take care of dulling the emotion.  
“If you’re not scared then watch the movie.” That same grin from before remains present on his face. Dib’s watched this movie before. He’s seen a lot of the ones that they’ve watched already, actually. He’s been there for almost half a day and known most of the movies by the first minute. Cons of being an avid horror fan. This particular one has a jump scare every minute unlike the previous movies which were more psychological thrillers or just bad, so it’s understandable that Zim would be at least a little frightened if he hasn’t already watched it. Dib knows that the biggest jump-scare is coming up soon if remembers correctly.  
“I am! I haven’t been scared by the others and this one is no different! Silly human emotions.” He chuckles mainly out of nerves before sitting in the centre of the sofa between the crevice of cushions. Dib watches on with eager intent to see his reaction as the alien frowns in concentration, trying to prove himself. A few minor scares and spooks barely budge him as he laughs at high volume from the triumph, “See! I told you that I am not-“  
As if it were queued by the gods, the loudest possible gunshot followed by a bloodcurdling scream projects from the television. Caught off guard by this, Zim leaps out of his seat and dives into the closest object to grasp onto it for safety. Usually it’s GIR who just offers him some sort of ridiculous snack, but today it’s a chortling and extremely warm Dib.  
Zim buries his face into Dib’s hot stomach and clenches onto the shirt by his waist; antennae pressed flat against his head. A quiet and frustrated grumble starts to evolve from the quivering alien who realises he’s just made a fool of himself.  
“You alright there, nerves of steel?” Said Dib who’s now sat upright with legs straight across the sofa with Zim placed nicely on his lap. If he wasn’t overheating already, now he has what’s practically an angry heater buried in his shirt. He’s laughing, but the positioning’s a bit awkward. If his head was just a little further up then that’d be fine, but it’s just a lot too close for comfort at the moment.  
Zim mumbles something with bitterness before letting out a long and very disappointed groan. Dib’s quite nice and warm, he may stay there if that’s okay. Plus he won’t have to watch the rest of the movie which is always a lovely bonus. “If you’re staying there I’m gonna have to shuffle a bit.” It’s a bit of an odd seating position, but then again their whole relationship is a bit odd anyway. Enemies to acquaintances in a month is a large step for both; it’s made a lot stranger with Zim being an alien, but Dib’s fine with weird.  
With an affirmative grunt coming from his stomach area, the awkwardly long boy brushes his cowlick back into place and shifts his butt. Much better, “you look like a cat sat like that.” Muses Dib as he reaches his hand to gently pat the scalp of Zim, brushing his nimble fingers against the base of the thick, black antennae causing Zim to flinch and prick them both up involuntarily. Seeing this as an opportunity to bully Zim (though they don’t fight, they still pick on one another from time to time) Dib continues prodding and poking at his antennae with increasing force until he grabs the base of one and tugs gently, “is this like your ear or something?”  
The unwarranted touching of his antennae was certainly a little uncomfortable (though he couldn’t put his finger on why) the small tug at the base sends a current running over his skin. With the realisation as to why the discomfort felt so foreign to him, Zim pushes away from the source of warmth to retreat to the other, colder side of the sofa. His expression is stern, but his cheeks say otherwise.  
This is definitely a new discovery, thought Dib, and also something he doesn’t like. Quickly shifting his weight to kneel and scramble over to Zim so he can grab at his antennae to bully him even more than before, Dib chuckles with a devilish tinge. For being 19 he still acts like a 10 year old at times; mostly with Zim.  
As the skinny human reaches over with his long arms and grasps at the top of the alien’s antennae, Zim attempts to kick him away to no real avail. The only thing he accomplished with his struggle was pushing himself closer to the Dib-beast. All this rough tugging and pulling doesn’t hurt, oh no, it’s no where near hurting. Zim’s yelling at the unknowing human doesn’t seem to deter him either but rather eggs him on in his insistence of pulling his antennae.  
Dib’s too taken up with inspecting each reaction and joint in the twitching pair of antennae in his hands that he barely gauges the reactions of the flustered alien below him. It’s only when the film falls silent that he can hear the quieter and softer complaining and pants of his newfound acquaintance.  
“Okay I know you’re trying to make me uncomfortable with this but it’s not gonna... work...” with nervous laughter, he looks down at the glassy, cherry eyes of the victim of his curiosity. It takes a few seconds and an adjustment of his slipping glasses, but Dib breaks the prolonged eye contact and sudden tension between the two, “are... are you getting off on this?” A wonky smile sits on his lips with antennae still in hand.  
“No! No you are disgusting and filthy!” It was odd for Zim to realise that he genuinely liked... this. His antennae aren’t for human hands and fiddling like some toy, but despite everything in his mind screaming no, his body yells back a tingly and affirmative yes. He weakly kicks at Dib’s crotch but barely misses by a hair’s breadth, “Unhand me! Unhand me now!” He wriggles around in his grip, Dib’s free hand now placed on the alien’s shoulder with his weight pressed into his palm, but each squirm and twitch just adds to the strange feeling pooling at the base of his torso.  
“You ARE getting off on this... huh...” a fleeting thought of taking advantage of the situation passes through his mind before being pushed out by the rational side of Dib. ’He’s your friend- nemesis- acquaintance- whatever he is, he’s not whatever is going through that big head of yours’, he reasons to himself as he idly stares in deep thought. Snapping out of the self inflicted trance, he evaluates what’s going on in front of him.  
Dib’s always liked Zim, but it’s not the same definition of ‘liked’ with each new revelation. When they first met, he liked him as an enemy. Intellectually similar while challenging him to think for once. He enjoyed the attention Zim gave him unlike the actual humans on earth. As he grew up, he started to consider him as more of a friend who pretends to hate him. Play fights and petty comments while also inadvertently helping one another out. There was mutual respect for their situations while also putting up that nemesis facade the whole time with fear of admitting they were friends.  
Once Dib hit 17, he realised he’d spent 7 years of his life with one person. Of course he’d had the odd ‘accidental fantasy’ with a guilty wank after each one, but it was one day that made it click. That transition from friends to “oh shit” which has been repressed for 2 years. It’s the reason he proposed the truce last month.  
Two years ago, it was christmas eve. Dib had a massive argument with his dad over an early present which was a roundabout way of getting Dib into ‘Real Science’. Dib had stormed out at midnight to knock on Zim’s door; frozen tears stuck to his cheeks as his cowlick hung down from under a messily put on bobble hat. Zim had invited him in because he looked ‘pathetic’ and made Dib cocoa with way too many marshmallows. He didn’t complain. It was a long, awkward few hours with a snivelling, shivering human sat at Zim’s side, but it was when Zim covered Dib’s frail body with a warm blanket and a quick pat on the head that set it all off. The closeness of Zim’s soft yet cold skin and the natural smell wafting off as he moved so carefully around him. It was that moment. That one moment that still plays in his head two years later, along with a few close interactions that almost rival the want for Zim.  
So that was the situation. Act upon some two year long wontedness towards a now vulnerable Zim, or keep his composure because it wasn’t ‘right’. Dib had always been the compulsive type, acting before thought, so once the options were laid out in front of him (quite literally in this case) he went with his gut.  
“What if...” he laughs to himself and lowers his hand to the very base of the left antennae before lightly massaging it with his forefinger and thumb, “what does that do for you, tough guy?” He’d always wanted to watch Zim melt before his eyes, whether it was through pure pain or pure bliss. He hopes that it’d be bliss now.  
Zim flinches as the new movement pulls him out of an internal conflict. He’d come to terms with his defectiveness but never learned to agree with his feelings towards the human above him. It’d become a habit of Zim’s at this point. Have weird, tingly feelings about Dib and immediately repress them. Put on that strong mask and dismiss everything but instinct. Instinct now, however, was a lot more untameable and primal than ever before. He lets off a small hum in response; eyes screwed tight and head falling to the side. It strikes a nerve in Dib’s stomach as his pupils dilate, drowning out the caramel with black pools of desire. His smile drops,  
“H-holy shit... uh...” is he taking this too far? What if Zim doesn’t want this at all? A pang of guilt strikes his heart as he examines Zim’s body language, loosening his grip on the twitching antennae. A strong smell of sweetness arises from underneath Dib followed by a pair of angry eyes boring into him,  
“What are you doing?” Overwhelmed by the flood of raw emotion, Zim takes the situation into his own hands. He understands what he’s feeling now as he’s experimented with himself previously on Irk, unknowing that self breeding was seen as taboo until he was told so. This situation, however, feels a lot nicer. Being handled by someone else, especially Dib as wouldn’t let any other human even lay a finger on him, set off some subconscious need in Zim, “useless human.”  
With his legs coiled up, he pushes Dib away and onto his back; the back of his head hitting the arm of the sofa,  
“Sorry! Sorry I didn’t mean to- I’m just- uh I’m being weird,” propping himself up slightly, he follows the alien’s hand movements as he adjusts the soft fabric of the dress that had ridden up; the sweet scent masking his skin, “look if I did anything wrong we can just-“  
His sentence was cut off, not by the usual yelling and commanding Zim spurts out in moments of rage, but rather by the sight of bedroom eyes coming from the approaching alien, crawling up to sit on his stomach,  
“you just don’t know when to quit,” though he’s not stood over Dib like before, the threat feels a lot more real than previous attempts. It was the placement of small, gloved hands on Dib’s chest followed by their eyes suddenly becoming level as Zim pulls Dib up by his collar that prompted the silence to break, “it’s a good job I don’t want to quit.”  
And that was it. 7 years of tension melts away into a passion and rage filled crash of lips and eventually tongues. It was time for Zim to make the first move, especially after Dib made the truce. This was the heat of the moment one up that Zim had and by god he was enjoying every second of it.  
Gasps for air as a segmented tongue explores the insides of Dib’s mouth escape between each kiss. It was messy and heated as strings of saliva pull away from every freshly made contact; made messier by Dib’s wondering hands grasping back at the flinching antennae’s base, the other hand pressed up against the curvature of Zim’s back.  
Zim didn't particularly like the feeling of the mammalian stubble Dib seemed to possess, but the taste more than made up for the discomfort. Bodies came closer, pressed up as much as possible, before both agreed wordlessly to take a breath.  
Red-faced, Dib takes a moment to add his vital opinion on the matter, “shit.” He expected that to be the end of it. Nothing else as that was wishful thinking. It was just Zim acting upon instinct, but for Zim his instincts hadn’t even had a real say in the majority of his actions. No, this was conscious thought and he knew exactly what he was doing.  
“If you wish to undress me then just know that I am keeping the gloves on.” Lifting his arms up, Zim sits himself on Dib’s crotch. Humans are so warm and lumpy, but this particular bump made the man underneath him jump and groan; face full flush with arousal and mild embarrassment.  
“You mean you.. you wanna?” Reaching down for the base of the supple tunic, he sits more upright than previously,  
“Quick! Before I change my mind, Dib-beast.” He wouldn’t change his mind but the mind numbingly slow way that Dib moves around him is starting to get on his nerves. Threats seem to work as the pace his uniform is removed at almost triples, as well as the excitement in Dib’s face. It’s nice to know he’s wanting it as much as Dib is.  
As he nervously fumbles around the overly complex uniform, Dib manages to reveal pieces of flesh that get his heart racing. He’s wanted to know what Zim looked like under his uniform for years and now he gets a taste. Not just a taste, a full buffet hopefully. His body, though alien in some senses, is surprisingly more humanoid than Dib had initially expected. It was the small waist and wide hips that shocked him the most out of anything,  
“Woah.. you’re so pretty.” Dib has a tendency to think out loud without even realising. It usually doesn’t aid his situation however this is an exception,  
“Yes I know. I’m amazing.” Zim thrives off of compliments though he gets very few. They often come from a place of sarcasm which he struggles to understand, but Dib has only genuinely complimented him a few times in his life. Though Zim plays it off, internally he’s set alight, “You’re not so bad yourself.” In Zim’s opinion, Dib’s one of the less horrible looking humans. Conventionally attractive? No, not at all, but there’s something about him that makes him special. Makes him stick out in Zim’s brain.  
“May I?” Dib reaches with gentle hands to lift Zim’s chin up, evaluating his clean-cut jawline and supple skin on his hardy fingertips. Without a reply, Dib takes it upon himself to place a soft peck on the sweet smelling neck of Zim. It’s nice and loving which is a pleasant break from the awkward tension. It’s quickly shattered by Zim shuffling around on Dib’s crotch with bated breath,  
“Okay I get it, Zim.” A fiddle with his drawstrings and a readjustment of the squirming alien later, Dib’s down to his space print boxers, slightly dampened by Zim’s movement rubbing him in all the right ways, “better?” At this point only his tunic is off, leaving a lot of flesh left to be desired. His arms and thighs being a few things Dib wants to see. He’s also deeply curious about what lies between his softened legs.  
“You can do better than that.” Zim’s brattiness and impatience gets the better of him as he swiftly yanks down the rim of Dib’s boxers, revealing a rather relieved member after being squashed for a long while. Dib’s always hated his dick, not because it’s wonky or anything, but it’s more along the lines of being below average. He’s compared himself to a lot of guys and found he’s not the most endowed man in the world. No matter what Dib thinks, Zim finds it rather intimidating. Small to Dib is something completely different to Zim,  
“Sorry if it isn’t that impressive. Honestly I don’t think-“ Zim cuts Dib off, yet again, with a gloved hand reaching around the base of his cock. He can barely get his fingers around it, so he frees his second hand to assist, “h-holy fuck-“ his dick twitches in agreement as Zim’s cold hands explore his anatomy.  
“Be quiet. And stop apologising!” Zim snaps up towards the excited Dib who stares down with love drowned eyes. With a good few seconds of Zim evaluating the length and width of the object in front of him, he nods with a firm hum, “Yes, that’ll do nicely. Dib!” He snaps Dib out of his horny state with a shrill command, “I have decided that I will let you breed me.”  
“Breed you?” Zim nods as he wriggles out of his skintight uniform covering his legs; the boots peel off with the leggings revealing his soaked, sweet smelling slit to the humid air, “I mean... gladly.” One look at the faux confident Zim with the dripping state just by the base of his crotch immediately makes up his mind. He can barely believe this is happening.  
Dib watches each and every move as Zim slides with ease over the head of his cock. Self lubricated and no male genitalia? Dib will have to make a note of that later. Not right now, of course. As the alien lowers himself to the very base, both let out a hefty sigh of bliss, “hah- you- you’re really fucking wet.”  
“I know, Dib-beast.” Biting at the thin resemblance of a lip, Zim attempts to keep his composure. He knows he’s safe on the actual breeding front as Irkens have their reproductive organ removed at birth, so the only thing he feels is pleasure and a little sore at the size. His skin is pushed out from the inside as Dib’s cock pushes up against the interior of his slit. The sweet scent starts to overpower the room as Zim takes it upon himself to start the rhythm.  
Antennae flinch and fall forwards towards Dib’s reach as the alien starts to ride his way towards the inevitable climax. He’s never experienced something as physically overwhelming as this, so it’s understandable that Zim wouldn’t last long.  
Taking the chance to bring the control back in his favour, Dib grasps at both Zim’s thin waist and the antennae offered to his palm. Once both were in his firm grip the pace immediately quickened. Translucent, pinkish liquid drips down the legs of the increasingly desperate alien and pools around the base of Dib’s cock. The gentle slap of skin to skin contact quietly resonates through the room as both parties sync up their breathing. Dib starts to lose his glasses at the intensity of each movement,  
“Is that all you’ve got? Pathetic!” Zim, though melting away at every lower and contact of skin, taunts at Dib who’s admittedly not trying his absolute hardest. Zim soon regrets his statement as Dib responds a bit too well to the criticism, putting all of his energy into fucking the life out of the little alien while muttering praise the whole time; legs bunched up behind Zim’s ass. Dib obviously liked a good brat.  
Zim grabs onto Dib’s waist as he’s pushed to his physical limit which he soon surpasses with surprising ease. Shivering and groaning at the sudden release, he looks down to find the sofa fully soaked with fluid. It was quickly followed with a few good pumps by Dib into Zim’s already quivering slit, leaving both drained almost completely. Zim isn’t usually exhausted but he is now and it’s clear that his exhausted human is too as Dib’s arms flop to either side; head falling back to hang off of the sofa’s arm. Zim lifts himself away before shuffling to lay on Dib’s stomach, a pleased grin lay resting on his face,  
“You’re not too bad for a human.” In tired response, Dib lifts his right arm to limply pat Zim on the head followed by a long groan, “you’re welcome.”  
Dib looks over at the screen to see that the TV had been turned over to some strange cartoon and as he shuffles away from the wet patch on the sofa he realises that he’d been sat on the remote. Ouch. Dib sits for a moment as Zim takes up all of his warmth, muttering about the amount of sweat he’s produced. Is the truce still on? Have they just broken it? Was this a one time thing? Dib sits and considers it for a moment before finally asking Zim a question with a frog in his throat,  
“So... what is this?” He waits in anticipation for Zim’s reply, expecting for the worst or at least a snarky comment. Instead he got something a lot more pleasant,  
“An experiment... And I think it was a success.”


End file.
